Recovery process

ABSTRACT

A process for economically recovering carbon black, oil and fuel gas from vehicle tires is disclosed, for either whole tires or physically fragmented tires. The tires are washed to remove dirt and road film. The clean tires are dried and preheated with super-heat steam. The hot tires are pyrolyzed to partially devolatize a major portion of the hydrocarbons and produce a char that can be separated from the steel and fiber glass. The char is subsequently pyrolyzed with microwaves that elevate the tire temperature and devolatize the remaining hydrocarbons from the char as gas. The hot gases are cooled and partially condensed. The uncondensed gas is used as fuel. The condensed oil is sent to storage. The solid residue from the tire pyrolysis is char, fiberglass and steel. The char is mechanically separated from the glass and steel. The char is milled to break down agglomerates and subsequently pelletized and bagged. The steel and glass are discarded as trash.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Application Ser. No.660,420, filed Oct. 12, 1984, by Fred Apffel, entitled "RECOVERYPROCESS" which is now abandoned.

FIELD OF THE INVENTION

The invention relates generally to processes for economically recoveringcarbonaceous materials from used vulcanized articles. More specificallyit relates to an economical pyrolysis process for recovering carbonblack, oil, fuel gas and steel from used tires.

BACKGROUND OF THE PRIOR ART

Passenger cars and trucks on U.S. highways wear out tens of millions oftires each year. Disposal of these used tires has become a majorenvironmental problem. A high proportion (up to 30-40%) of the weight ofa used tire consists of carbon black reinforcing of the rubber in boththe tread and sidewalls. This carbon black is prepared by conventionalcarbon black production processes and comprises individual particles onemicron or less in diameter. Fifty to sixty percent (50-60%) of theweight of a discarded tire is butadiene-styrene copolymer rubber. Tiresalso contain large amounts of oil and significant quantities of steel,wire and/or fiberglass or polyester cord. All of these components areexpensive and require large amounts of energy in their manufacture. Aprocess that would allow economic recovery of these materials from thehugs stocks of used tires piling up around the country would be verydesirable. Unfortunately, the very characteristics that make tireslong-lasting and safe of the road, i.e., durability, resistance topuncture and slicing, and resistance to decomposition at moderatetemperature, combine to make tires exceptionally difficult to recycle.

The prior art teaches the rubber can be pyrolyzed in the absence of airat temperatures of between 842° and 1112° Fahrenheit in laboratoryequipment to produce oil, gas and solid residue that is carbonaceous innature. Large electrically heated sink reactors and Dewar flasks havebeen used for otaining test data.

The prior art also teaches some pilot plants that were built to carrytire processing schemes into the commercial world. Circulating heatedceramic balls have been used a direct source of reaction heat. The ballsare heated externally, mixed with rubber feed chips, discharge,screened, reheated and recycled. These reactions take placesubstantially at atmospheric pressure. Other pilot plants have beendesigned which make the carbonaceous solid phase of tire pyrolysis intofuel briquets. These fuel briquest are much less valuable than thecarbon black produced by the present invention. Still other batch pilotplants have been built in which the tires are indirectly heated throughthe tray walls of multi-tray reactors to temperatures of between 1400°and 1600° Fahrenheit. At these temperatues, heavy oils and tar productscan be recycled for further cracking to improve carbon black yields.Other batch and continuous type process plants have been built thatdepend on indirect heating through walls of a jacketed screw reactorfrom a high temperature molten salt heat sink. Other continuous typeprocess plants have been built that depend on indirect heating throughhollow shaft and hollow flight screw conveyors from a high temperaturemolten salt bath, which also use the carbon black for commercialpurposes as carbon black.

In each of the prior plants set out above, the heat must be transferredindirectly from a heat source to a solid tire particle through a wall ordirectly through heated ceramic balls. Indirect heating as the solemeans of heat transfer causes coating and other nonuniform heatingproblems.

It is an object of the present invention to overcome these problems, andheat the tires directly without direct physical intrusion into theprocess reactor.

Also, in each of the prior art types of pyrolysis plants set out above,the tires were required to be physically broken apart into smallerpieces or fragments except those that show direct melting of held wholetires. Commercially available tire disintegrators include slicingmachines, hammer mills, debeaders and manglers that have been adapted totire reduction from other industries. The recent introduction of steelreinforcing in both passenger and truck tires has greatly increased thedifficulty and expense of sufficiently disintegrating a tire to convertit into a useable pyrolysis feed stock.

It is another object of the present invention to overcome the physicaldifficulties of the prior art in preparing used tires as a feed stock byprocessing whole tires.

It is also believed that the prior art has never taught a satisfactorymethod of completely devolatizing the heavy oil and tars that coat theresidue carbon black particles due to the limitations of indirectheating or contact direct heating.

It is a further object of the present invention to teach a method ofdirect heating that fully devolatizes the oil at the carbon blackparticle thus producing a carbon black with properties equal to that ofthe original carbon black.

It is yet another object of the present invention to teach a method andan apparatus for pyrolyzing used tires economically into commercialquantities of oil and fuel gas.

It is still a further object of this invention to teach a method ofrecovering steel scrap from used tires.

It is yet another object of the present invention to teach a method ofpyrolyzing used tires that is energy efficient and generates fuel gasnecessary to operate a large part of the process within environmentalregulations from the process itself.

It is yet another object of the present invention to teach a method ofand teach apparatus for pyrolyzing used tires economically intocommercial quality and quantities of carbon black.

BRIEF DESCRIPTION OF THE INVENTION

The invention is a process for economically pyrolyzing used tires intocommercial quantities of carbon black, fuel oils and fuel gas.

Whole tires are preferably prewashed to remove dirt and road film. Theclean tires are conveyed to a stean preheating chamber where they areheated to a temperature level of 200° to 500° Fahrenheit. The steamheated tires are dumped through a three-stage gate system into a radientheated stainless steel or refractory lined steel pyrolysis chamber. Herethe tires are conveyed along by a flat-bed stainless steel conveyor. Amultiple number of tubes heated to 1500°-2000° F. external to the tireschamber produce the radient heat that supply the energy to pryolize thetires and partially devolatize the hydrocarbons as a gas.

The radient energy heats the tires to a temperature level of 800° to1000° Fahrenheit. The temperatures are controlled at levels of 800° to1000° Fahrenheit by measuring the pyrolysis gas exhaust gas temperatureand increasing or decreasing the input of fuel oil or gas.

The volatile hydrocarbon gases exit the pyrolysis chamber through acyclone separator where entrained dust is removed. The dust leaves thebottom of the cyclone through a rotary lock to recombine with charproduced from the pyrolysis of the tires.

The dust-free gas is fed to a direct oil condensing spray chamber wherethe heavier oils are condensed to a temperature level of 140° to 180°Fahrenheit. The condensed heavy oil product is subsequently sent tostorage. The uncondensed gases are then further cooled in a conventionalwater cooled exchanger to approximately 100° Fahrenheit and furthercondensation results. The mixture is then fed to a three-phase separatorwhere the uncondensed gas, water and oil are separated. Then thecondensed oil is sent to storage; the gas is compressed and used asplant fuel; and the water is processed through an oil water separator toremove the final traces of oil, which is stored, and the water issewered.

The char from the pyrolysis chamber is dumped through a gate system intoa rotary screen system where the char is separated from the steel andfiberglass. The steel and fiberglass are cooled, and the steel isseparated from the fiberglass magnetically. The char is processedthrough a rotary lock into a final char pyrolysis chamber where it isheated to 1500°-1600° F. to remove the final traces of volatilehydrocarbons from the char. The devolatized char is processed through arotary lock into a hollow flight screw conveyor where it is cooled toambient levels of temperature. After cooling the char is milled to afine power, subsequently rolled into pellets and bagged as a carbonblack product.

The devolatized hydrocarbons are withdrawn from the system and combinedwith other gas in the dust cyclone separator.

The partial devolatizing of the tire with radient energy accomplishestwo major process tasks. The first is the reduction in microwave energyrequirements when pyrolizing char to roughly one-fifth of that requiredfor pyrolyzing whole tires. The second is the elimination of a potentialarcing problem that might occur with the steel wire contained in thewhole tire when microwave energy is applied to them.

DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference is made to the following drawing in which likeparts are given like reference numerals, and wherein:

FIGS. 1A, 1B and 1C are a flow diagram of the preferred embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The process shown schematically in FIGS. 1A, 1B and 1C comprises:

1. Feed Preparation

2. Steam Preheat

3. Radient Tire Pyrolysis

4. Vapor Recovery

5. Solid Separation

6. Char Pyrolysis

7. Char Milling and Recovery

8. Pelletizing and Pellet Drying

These sections are discussed in detail below.

1. Feed Preparation

As illustrated in FIG. 1A, whole tires (not shown), or pieces ifpreferred, entering at 10 are fed into the process through a chamber 64of a three-stage gate 11. The tires are cleaned (not shown) prior toentry into chamber 64. Two gates 61, 63 of the three gates 61, 62, 63operate simultaneously, opening and closing together. The third gate 62is closed when gates 61, 63 are opened and open when gates 61, 63 areclosed. This permits a tire to enter gate chamber 64 with gates 61, 63closed. Thereafter gates 61, 63 open while gate 62 is closed to permitthe tire to enter chamber 65. Chamber 65 is defined by the space betweengates 61, 62. Gate 62 then opens when gates 61, 63 are closed andpermits the tire in chamber 65 to drop into chamber 66. Chamber 66 isdefined by the space between gates 62, 63. Gates 61, 63 then open aftergate 62 closes thereby permitting another tire in chamber 64 to dropinto chamber 65 and the tire in chamber 66 to drop into chamber 67 forthe tire preheater 12 below chamber 67. The cycle of gates 61, 62, 63opening and closing is then repeated. These gates, complete withcontrols, may be purchased from Fuller Gate Company.

2. Steam Preheat

Whole tires, or parts if desired, enter the tire preheater 12 throughchamber 67 where they are brought into direct contact with super heatedsteam from steam 58. The entering steam is at temperatures of 500° to600° F. and pressures of 5 to 20 psig. The tires are heated from ambienttemperatures of a range from 80° to 120° F. to a level of 300° to 450°F. During the heating in the tire preheater 12, the whole tires arecontinuously conveyed from the entry of the tire chamber 12 to the exiton a flat bed steel conveyor 60. The hot tires exit tire preheater 12via gate 13. Gate 13 is substantially of the same construction andoperation as gate 11. In addition to acting as a preheater, the tirepreheater 12 acts as a seal between the environment and the pyrolysischamber 18, leaking steam or water to the atmosphere as opposed to thegas generated from the pyrolysis of the tires.

3. Radient Tire Pyrolysis

Preheated whole tires, or pieces if desired, enter the tire pyrolysisunit or chamber through gate 13. The pyrolysis chamber is preferableconstructed of high temperature alloy steel or refractory lined steel.The units and operating components should be constructed of hightemperature alloy steel or equivalent material because of the hightemperatures. The tires are conveyed from the entrance of the steelpyrolysis chamber 407 to the exit on a flat bed stainless steel conveyor406. The energy to heat the tires from 200° to 500° F. to a level of800° to 1000° F. at -5 to 20 psig is achieved by multiple number ofradient tubes 409 (one of these shown schematically and as illustrationin FIG. 1A). Each of the radient tubes 409 are heated internally to atemperature level of 1600°-2000° F. Both radient and convection heat aretransferred from the tubes 409 to the tires moving through the tirepyrolysis chamber 407 on the conveyor 406. The tires are heated totemperatures of 800° to 1000° F. The volatile hydrocarbons are partiallydecomposed as gas from the tire and exit in conduit 405 to the cyclonedust separator 20.

The temperature of these gases in conduit 405 is measured by thetemperature sensor 404 and control the amount of fuel to the burner 403,using the fuel control valve 401.

The burned gases produced in the radient tube 409 exit at a temperatureof 1000° to 1200° F. in conduit 410 and flows to the waste heat steamboiler 411 to produce steam for the steam preheater 12.

The char, steel and fiberglass exit the tire pyrolysis chamber throughgate 48 to the char, steel and glass separation system 49.

4. Vapor Recovery

During pyrolysis, hydrocarbon vapors separate from the tires in thepyrolysis units 18,407 and exit through the conduits 19,405. The hotgases at 1000° to 1100° F. and pressure to -5 to 20 psig are fed to acyclone dust separator 20. The cyclone dust separator 20 is designed toseparate any solid particulates that may hve been carried over with thepyrolyzed tire vapors. The cyclone dust separator 20 may be heated withelectrical strip heaters (not shown) to maintain the gas temperature andprevent condensation of any liquids before the carbon dust is separatedfrom the gas. Several cyclone dust separators may be used in series tofurther reduce the solid particulate matter in the gas if necessary. Thecyclone dust separators should be constructed of stainless steel orequivalent material because of the high temperatures.

The hot gas exits from the cyclone dust separator 20 in conduit 21 tothe direct contact spray condenser unit 22 which acts as both a partialcondenser and a final carbon black dust scrubber. The lighter oil iscondensed separately to permit more effective separation of water vaporfrom a lighter oil. Should there be any carry-over of carbon black dustfrom the cyclone dust separator 20, it will be removed in the heavyoil/gas separator 26 and allowed to settle to the bottom of theseparator 26 where it will be removed as sludge. Light oil from storageis also introduced via conduit 23, at a pressure of 10 to 200 psig and atemperature of 80° to 120° F., to the direct contact spray condenserunit 22. The amount of oil introduced is controlled by a temperaturecontroller 67, having a sensor in the roof of heavy oil/gas separator26, and control valve 68. This temperature is set at 200° to 220° F. Theoil is fed to the spray nozles 24, 25, such as hollow cone nozzles. Thenumber of spray nozzles are illustrative and no limitation as to type ornumber is intended thereby. The fine spray from the hollow cone spraynozzles 24, 25 both cool and partially condense the hot gases fromconduit 21.

The condensed oil and uncondensed gas flow into the heavy oil/gasseparator 26. The condensed heavy oil exits in conduit 38 to pump 39where it is pumped to water cooler 206 via conduit 40. The heavy oil iscooled below 140° F. The heavy oil exits the water cooler 206 viaconduit 29 to storage. Flow of the heavy oil to storage is controlled bythe level control sensor 204 and level control valve 203.

Sludge, or heavy oils containing solid particulate, exit at the bottomof the heavy oil/gas separator 26 via conduit 41 to pump 42, and ispumped to storage via conduit 43. The amount of sludge removed isachieved by adjusting the speed of pump 42 which is a gear-type pump,driven by a direct current motor and controlled by speed controller 205.Laboratory analysis will establish the level of solids in the sludge andwill be used to set the flow rate.

The uncondensed vapors exit the heavy oil/gas separator via conduit 27to a water cooler condenser 28 and reduced to temperatures of 80° to100° F. These partially condensed fluids are fed, via conduit 30, to thethree-phase water/gas/liquid separator 31. The separated, uncondensedgases exit the gas/liquid separator 31 in conduit 32 and are fed to thecompressor 33 to elevate the pressure to a level of 20 to 30 psig. Thesecompressed gases are then fed to a fuel system (not shown) via conduit34, and may be used in thedrying process for dryer 126 discussed below.

The general chemical composition of the uncondensed fuel gas is shownbelow:

                  TABLE I                                                         ______________________________________                                        Tire Pyrolysis Fuel Gas                                                                          Volume Percent                                             ______________________________________                                        Carbon Monoxide     7 to 12                                                   Carbon Dioxide     4 to 8                                                     Parriffins         20 to 35                                                   Olefins            35 to 45                                                   Other Hydrocarbons 10 to 15                                                   Water Vapor        3 to 8                                                     Average Mol Weight 36 to 42                                                   Heating Value, Btu/1000 ft.sup.3                                                                 1800 to 1900                                               Vol/Ton of Tires, SCF/Ton                                                                         600 to 1000                                               ______________________________________                                    

The water separates from the oil and is further processed to remove thefinal traces of oil in an oily-water filter separator portion ofseparator 31. It is subsequently pumped to a water storage tank or sewervia conduit 72 and pump 73 to and through conduit 74.

The light oil is pumped to storage via conduit 35 and pump 36 to andthrough conduit 37. This light oil may be used as the oil for conduit23. A level control sensor 202 and level control valve 205 controls theflow rate of the light oil from the three phase water/gas/liquidseparator 31.

After the water has been removed from the light oil, the light and heavyoil will be recombined as a composite oil.

The physical properties of the composite oil recovered is provided inTable II below:

                  TABLE II                                                        ______________________________________                                        Pyrolysis Oil From Tires                                                      ______________________________________                                        Volume/Ton of Tire, Bbl/Ton                                                                      2.5 to 3.1                                                 Average Molecular Weight                                                                         190 to 230                                                 Heating Value (Btu/lb)                                                                           17,000 to 19,000                                           U.O.P. K-Factor    10 to 11                                                   Total Sulfur, Wt % 0.1 to 1.0                                                 Total Chlorides, Wt %                                                                             0.0 to 0.01                                               Specific Gravity @ 60° F.                                                                 0.7 to 1.1                                                 Specific Gravity @ 150° F.                                                                0.8 to 1.0                                                 Viscosity, CS @ 60° F.                                                                     8 to 15                                                   Viscosity, CS @ 160° F.                                                                   1 to 5                                                     Reid Vapor Pressure                                                                              1 to 3                                                     Pour Point, °F.                                                                           -20 to -10                                                 Ash Content, Wt %  0.02 to 0.3                                                ______________________________________                                        ASTM Distilation Profile                                                      Volume                                                                        Percent Distilled                                                                            ASTM Boiling Point                                             ______________________________________                                         5             110 to 140                                                     50             550 to 600                                                     95              850 to 1000                                                   ______________________________________                                    

5. Solid Separation

Char from the cyclone dust separator 20 is processed through rotaryvalve 44 to a screw conveyor 45. The char exits screw conveyor 45 viarotary valve 46 and conduit 47 where it is fed to char pyrolysis chamber18.

Steel, glass and char from the pyrolysis unit 407 are processed throughgate 48 to the rotary screen system 49. Gate 48 is similar inconstruction to gates 11, 13.

A rotary screen 50 is mounted within system 49. Screen 50, with, forexample, 1/2 to 1 inch holes, moves back and forth causing the char toseparte from the glass and steel. Ultimately, the char falls into thescrew conveyor 51. The rotary screen system is tilted at an angle, suchas approximately five degrees, and the glass and steel eventually morefrom the entryway to the exit as a result of the rotary motion. Thesteel and glass exit in conduit 76.

FIG. 1B illustrates the flow of the steel and glass from conduit 76. Thesteel and glass are processed through gate 69 to a steel flatbedconveyor member 71 in conveyor chamber 70. Cooling water is sprayed inthis chamber to reduce the temperature from 1100° F. to a level of 250°to 300° F. This is achieved using spray nozzles 98, such as hollow conespray nozzles, to permit influx of water. The number of spray nozzlesare illustrative, and no limitation is intended thereby. The fine sprayfrom the hollow cone spray nozzles 98 cool the glass, steel and dustvapors. The dust vapors, having dust, char and vapor, exit chamber 70 inconduit 81 where additional cooling water is added to cool these vapors,to the extent necessary, below 150° F. The amount of water fed to theconveyor chamber 70 is controlled by a control valve 75 and temperaturecontroller 77 having a sensor mounted in the chamber 70. The amount ofwater fed to the conduit 81 is controlled by the temperature controlvalve 78 having a sensor mounted in conduit 81.

The cooled char, dust and vapors in conduit 81 is fed to a cyclone dustseparator 83 via conduit 81. The dust or carbon black char separatesfrom the vapors in the cyclone dust separator 83 and fall to the bottom.The dust is discharged from the cyclone dust separator 83 via rotaryvalve 90 into conduit 91 and subsequently into a screw conveyor 93.

The vapors from the cyclone dust separator 83 exit via conduit 84 andare fed to the bag house filter 88. The bag house filter 88 containsfilter elements that separate the dust from the vapors.

The dust-free vapors exit from the bag house filter 88 in conduit 85 andare fed to a blower 86. The discharge from the blower 86 exits inconduit 87 and is fed to an incinerator (not shown).

The char solids settle to the bottom of the bag house filter 88 and exitthrough a rotary valve 89 into conduit 92. The char from conduits 91, 92are fed to the screw conveyor 93, and discharge through rotary valve 94into conduit 95. This char is subsequently fed as the third char feed tothe char cooler 55.

The cooled glass and steel are conveyed through the conveyor chamber 70to the exit gate 96 via conduit 99 onto a discharge conveyor 97 astrash.

6. Char Pyrolysis

The char from the screw conveyor 51, as illustrated in FIG. 1A, isdischarged through the rotary valve 413 and fed to char pyrolysischamber 18.

The char is heated to a temperature level of 1500° to 1800° F. usingmicrowave energy as it is conveyed through the char pyrolysis chamber18. The char pyrolysis chamber 18 is a refractory lined steel chamberwith a ceramic lined deck. A high temperature alloy chain 17, withceramic paddles, drag the char over the duct from the entrance to theexit of the char pyrolysis chamber 18. Alternately, a flat-bed hightemperature alloy steel conveyor may be used to transport the char fromthe entrance of the char pyrolysis chamber 18 to the exit.

The microwave energy is generated by a multiple number of microwaveunits (one of these is shown schematically and as an illustration inFIG. 1A). Each microwave unit includes a power supply 14, magnetron 15and waveguide 16. Each microwave unit generates power levels of five tofifty kilowatts. The number and type of microwaves and microwavegenerators are illustrative and no limitations are intended thereby.

The mechanism of microwave heating of carbon black is that of ionicconduction. Free ions exist at the interface of the carbon black and theremaining volatile hydrocarbons. These ions are not neutral, but ratherpositive or negatively charged. As such they are attracted by electricfields and their movement in such fields constitutes a flow of current.Their velocity represents kinetic energy. The ions do not travel farbefore they collide with unionized molecules, giving up their kineticenergy in a randomized fashion. This generates heat instantaneously. Theheat energy is penetrating and efficient and unincumbered by theinsulating effect of tire rubber that indirect heating systems mustovercome. The temperature of the pyrolysis chamber 18 will be controlledby measuring the hydrocarbon gas temperature that exists in conduit 19.This will be achieved by the temperature controlling sensor 200 whichwill transmit a signal to the microwave power generator 14 to increaseor decrease the power tomaintain the desired a temperature. If thetemperature reaches an unacceptable limit, a signal (by an interlock notshown) will be sent to shut the microwave system off.

Not all of the microwave power generated by the magnetron is absorbed bythe tires or the pyrolysis chamber 18. A large quantity is reflectedback to the wave guide 16 and could subsequently be reflected back tothe magnetron source 15. This would destroy the system. To prevent this,wave guide 16 is equipped with a ferrite circulator (not shown), orother "one way" valve, which permits microwaves to go forward to thepyrolysis chamber 18 but isolates the magnetron 15 from reflectedmicrowaves. An impedence matching device or tuning stub (not shown) isalso contained in the waveguide 16 which redirects reflected microwaves.The tuning stub is controlled by measuring the reflected microwaves witha reflected microwave power meter 201 and adjusting the tuning stub asrequired.

Entrance and exits of the pyrolysis chamber 18 will be equipped withstandard quarter wave reflective chokes (not shown) to prevent microwaveleakage to the environment.

The microwave units and the rest of the reactor system may be purchasedfrom Cober Electronics, Inc.

The char from the char pyrolysis chamber 18 is discharged through therotory lock 52 and fed to the char cooler 55 via conduit 53 located nearthe entrance of cooler 55. The char cooler 55 is a hollow flight screwconveyor and cooling water in conduit 58 is processed through the hollowflights to indirectly cool the char and exits through conduit 54. Thecooled char, cooled to approximately 100° to 120° F., exits the charcooler 55 through a rotary valve 56 into conduit 57.

7. Char Milling and Recovery

As illustrated in FIG. 1C, the inlet feed from conduit 57 to the charmilling and recovery section includes an aggregation of very smallparticles of carbon black and carbonaceous material cemented together ina skeletal matrix of residues from the decomposition of the tire rubber.The carbon black is from the carbon black portion of the tire. Thecarbonaceous material in the skeletal martrix is formed in thedestruction heat treatment of the rubber and heavy oils in the tires andacts as the binder for the individual carbon black particles in theskeletal matrix of the char.

The milling process of the present invention breaks down the charagglomerates into individual carbon black particles and much smalleragglomerates of carbon black particles, the agglomerates being, forexample, less than forty microns in diameter. Because different gradesare used in the tread and walls of the tire and because different tireproducers used different quantities of different carbon blacks, thecarbon black recovery by the present invention from the original tirecomposition is a mixture of commercial carbon blacks from many sourcesin varying proportions. Therefore, carbon black produced by the presentinvention is a mixture of commercial carbon blacks and new carbon blackand has mixed carbon black properties.

The char inlet feed, from the char cooler 55, passes by conduit 57 to amill 104 as shown in FIG. 1C. This mill can be a roller mill, ball millor hammer mill, all of which are commercially available. The mill 104 isair swept with a stream of air from blower 106. The mill breaks down thelarge agglomerates into individual carbon particles and smallagglomerates. These particles are then picked up by the flow of air viablower 106 through the mill 104 and carried to mechanical separator 108.Mechanical separator 108 functions centrifugally to remove largerparticles from the air stream. A portion of the heavy rejects from themechanical separator 108 and the mill 104, which comprise a stream ofless than five percent of the total mill feed, leaves the process astrash through conduit 110. Output stream 110 essentially eliminates allresidual fiberglass, unburned rubber, iron rust and heavy metallic ash.The remaining carbon black is conveyed by air stream 112 to cycloneseparator 114. Eighty to ninety percent of the carbon black is separatedhere from the air stream and conveyed to pelletizer 120 via conduit 119.The remaining carbon black travels with the air stream back through airreturn 116 from separator 104 to the suction of blower 106 where it iscompressed and recycled. Additionally, make-up air is also introduced tothe section of the blower 106 through line 117.

The major part of the discharge of the blower 106 flows directly to mill104 to sweep up dust particles as discussed above. A sidestream of airfrom blower 160 is also bled off to pass through conduit 123 and, underpressure, through bag filter 118 where the remaining carbon black istrapped and fed to pelletizer 120 via conduit 129. The air from bagfilter 118 is vented to atmosphere through conduit 121 and a blower 147.

Of course, the finer the char is milled, the better carbon blackproperties can be obtained. The embodiments of the present invention usean air swept roller mill with mechanical separators. This does a farsuperior job of grinding the char to a finer size using much less energythan the prior art.

In the present invention, it has been determined that a roller mill usedin combination with mechanical separators and a cyclone and dust bagseparator yields a process that can reject larger and heavier particlesof unburned rubber, residual ash and iron rust from the system withouttoo much loss of valuable carbon black. This system will also reject amajor portion of the residual fiberglass left in the char. An air sweptroller mill, with mechanical separators, can produce 99.9% by weightcarbon black product passing a 325 mesh screen (44 micron averageparticle diameter) and a reject stream of less than 5% of total millfeed that will essentially eliminate residual fiberglass, unburnedrubber, iron rust and heavy metallic ash.

It should be noticed that the present invention may recover twoproducts. Both the cyclone separator fines from conduit 119 and the bagdust collector fines from conduit 129 are recovered separately. Theseproducts can be mixed together as a common product as shown in FIG. 1Cor kept separate as two grades of carbon black. Because the bag filter118 fines in conduit 129 have been elutriated from the other fines, theywill consequently be of smaller average particles size, have lower bulkdensity and high specific surface. This will give them differentphysical properties from the cyclone separator fines in conduit 119.

At this point in the process, the carbon black must be pelletized toform a denser, more dust free pellet. If two products are produced, twopellets of the sort discussed in the next section will be used. However,without limiting the generality, a single pellatizer 120 is shown forillustration using a mixed product.

8. Pelletizing and Pellet Drying

Carbon black passes from bag filter 118 and cyclone separator 114 viaconduits 129, 119, respectively, to a feed stream to pelletizer 120.Such pelletizers are commercially available. Here the pellets are wettedwith water, delivered from hot water conduit 122, to pelletizer 120.This water may, in part, be the water that was heated by indirect heatexchange with other process flows. By "process flows" it is meant theoil products stream 27 and pyrolyzed solid phase carbonaceous materialstreams 47, 53, 95 that were cooled with indirect heat exchange withcold water.

Most commercial carbon black is pelletized with water or with suitablebinders. While uses want denser and more dust free pellets, they stillwant to retain the dispersion properties of unpelletized carbon blacks.

The present invention uses hot water (140°-180° F. and preferably at165°-170° F.) without a binder for pelletizing carbon black. Carbonblack has tremendous surface area per unit weight, and this surface mustbe completely wetted before stable pellets can be produced. Theembodiments of the present invention use 35-45 pounds of 170° Fahrenheitwater per 55-65 pounds carbon black dust to produce a suitable feed forwet pelletizing equipment. This water must then be driven off by heat inpellet dryers before the dry pellet (less than 1% moisture) is baggedand shipped. Extreme care must be taken not to degrade the pellet backto fines on drying. For ready dispersion after drying, it is alsonecessary that a soft pellet be produced from the pelletizer. Excessiveattrition must also be prevented in drying. In addition, theinterstitial moisture must be uniformly and slowly removed to preventdistintegration from excessive early steam generation.

The present invention used commercially available pelletizing equipment.

The wet pellets from pelletizer 120 are conveyed to a commerciallyavailable indirect pellet dryer 126, such as a rotary drum, via stream124. The indirect rotary dryer burns fuel from conduit 125 with air fromconduit 127 outside the shell of the dryer 126 and transfers the heatthrough the walls of the drying solids (not shown) inside the shellwhich is rotating. Because of the very high surface area of carbon blackpellets and the affinity of this surface for water, temperatures muchhigher than the atmospheric boiling point of water must be used toinsure that the pellets have discharged moisture down to the minimumresidual moisture of less than 1% by weight in the product pellets. Thedry pellets exit the dryer 126 in conveyor 128 at about 300° F. and0.45% moisture by weight.

The moisture laden flue gases from the indirect dryer 126 exits thedryer 126 in duct 134 and enters dust collector 136 at preferably about147° F. with a dew point of 119° F. The flue gas is cooled by theinjection of cooling water into the flue gas to maintain a temperaturebelow 150°. A temperature controller 208 measures the flue gastemperature in conduit 134 and signals the temperature control valve 207to open or close increasing or decreasing the water flow as required tomaintain the required temperature. A further spread of wet and drytemperatures is possible by bypassing part of the heated air from stagesof the dryers (not shown) and mixing with exit gases in flue 134 aheadof the dust collector 136. The dust filter is conventional as isrehandling of the collected dust. The collected dust travels throughconveyor 138 to reenter the pelletizer 120. The filtered air isdischarged through blower 146 and vent 140 to the atmosphere.

The pellets proceed from the dryer 126 along conveyor 128 to a doubledeck screen 130. This screen has a top screen that separates oversizedpelletizer formations from properly sized pellets and fines. The secondscreen is sized such that it retains the properly sized carbon blackpellets but passes the fines. Both the oversized pellets and the finesare recycled by recycle stream 132 into the mill 104.

Properly sized and dried carbon black pellets are conveyed out of theprocess by output stream 142, for bagging and bulk shipment.

9. Carbon Black Properties

Table III compares the chemical properties of the carbon black producedfrom this invention with a commercially available carbon black.

                  TABLE III                                                       ______________________________________                                        Comparative Chemical Properties                                                           Test       Recovered Commercial                                   Property    Method     Black     Black SFR-762                                ______________________________________                                        DBP Absorption                                                                            ASTM-D2414 74        75                                           CC/100 gm                                                                     Iodine Number                                                                             ASTM-D1510 52        30                                           C-Tab-Number                                                                              Phillips   55        35                                           % Ash                  13.5      0.5                                          % Heating Loss                                                                            ASTM-D1618 0.39      0.42                                         PH          ASTM-D1512 7.        8.5                                          % Sulfur    ASTM-D1619 2.2       0.5                                          ______________________________________                                    

Table IV compares the physical properties of the carbon black producedfrom this invention with a commercially available carbon black.

                  TABLE IV                                                        ______________________________________                                        Comparative Physical Properties                                                              Recovered                                                                              Commercial                                                           Black    Black SRF-762                                         ______________________________________                                        Basic Mixture                                                                 SBR.1592, gm     100        100                                               SRF-762, gm                 50                                                Recovered Black, gm                                                                            50                                                           Zinc Oxide, gm   3.5        3.5                                               Sulfur, gm       2          2                                                 Cumate, gm       0.1        0.1                                               Results                                                                       Modulus of Elasticity, 100%                                                                    420        380                                               Modulus of Elasticity, 200%                                                                    1120       1150                                              Modulus of Elasticity, 300%                                                                    1900       1989                                              Tensile          2299       2293                                              Hardness         68         66                                                Elongation       330        360                                               Min. Torque      18.1       13.8                                              Max. Torque      113.1      103.5                                             Scorth Time, Min.                                                                              5          15                                                Core Time, Min.  6          21                                                Tear             235        163                                               ______________________________________                                    

The yield of carbon black from tires is 0.36 to 0.42 tons per ton oftires processed.

The yield of steel and glass is 0.5 to 0.8 tons per ton of tiresprocessed.

The utilities requirements for the pyrolysis of tires using microwaveenergy is provided in Table V below:

                  TABLE V                                                         ______________________________________                                        Tire Pyrolysis Utilities                                                      ______________________________________                                        Microwave Electrical, KW/Ton                                                                       1 to 2                                                   Other Electrical, KW/Ton                                                                           0.1 to 0.3                                               Superheated Steam, Mlbs/Ton                                                                          2 to 2.5                                               Cooling Water, GPM   5 to 8                                                   ______________________________________                                    

Because many varying and different embodiments may be made within thescope of the inventive concept herein taught including equivalentstructures or materials hereinafter thought of, and because manymodifications may be made in the embodiments herein detailed inaccordance with the descriptive requirements of the law, it is to beunderstood that the details herein are to be interpreted as illustrativeand not in a limiting sense.

What is claimed as invention is:
 1. A process for manufacturing carbonblack and hydrocarbons from discarded tires, comprising:introducing thetires into a reactor; pyrolyzing the tires in a pyrolysis reactionvessel substantially in the absence of artificially introduced oilheating media at a temperature and pressure and for a reaction timesufficient to cause the tires to dissociate into a vapor phase and asolid phase; said pyrolyzing step including directly, internally heatingthe tires in the reaction vessel using microwave energy; producingcarbon black from the solid phase; and processing said vapor phase toproduce hydrocarbons.
 2. A process as in claim 1 including:separatingtrash from the pyrolyzed solid phase after said reaction; and millingthe pyrolyzed solid phase to carbon black.
 3. A process as in claim 2including:cooling the pyrolyzed solid phase after separation of thetrash.
 4. A process as in claim 3 including:wetting at least a portionof the carbon black; forming the wetted carbon black into pellets; anddrying the carbon black pellets.
 5. A process as in claim 3, wherein thecooling is accomplished by passing said solid phase in indirect heatexchange with water.
 6. A process of claim 2, wherein carbon black isfurther separated from said trash and cooled and milled to carbon black.7. A process as in claim 2, wherein milling of the pyrolyzed solid phaseinto carbon black is accomplished by passing the pyrolyzed solid phasethrough an air swept mill.
 8. A process as in claim 1, wherein the heatis introduced through microwave transmitters controlled by thetemperature of the hydrocarbon effluent.
 9. A process as in claim 1,including initially passing the effluent vapor phase from the reactorvessel through a dust separator.
 10. A process as in claim 9, whereinseparation of said dust of said vapor phase occurs in close proximity tothe vapor outlet of the pyrolysis reaction vessel.
 11. A process ofclaim 10, wherein the dust from the separator is cooled and milled tocarbon black.
 12. A process as in claim 10, wherein the vapor phaseobtained after dust separation is cooled to condense out oil and saidoil is separated from the gas containing remainder of said vapor phase.13. A process as in claim 12, wherein said oil is cooled out by directcontact cooling in a direct spray condenser.
 14. A process as in claim13 including:further separating light oil from the vapor phase bycooling; and compressing the gas containing remainder of the vapor phaseto provide fuel.
 15. A process of claim 1, wherein the tires are wholeand there is further included the step of preheating the tires prior tothe pyrolizing step.
 16. A process of claim 15, wherein the preheatingstep includes preheating by direct steam contact, forming a steam gasseal.
 17. A process as in claim 16, wherein the pyrolyzing occurs in anoxygen limited hydrocarbon vapor atmosphere isolated from ambient air bythe use of the steam gas seal and by the use of airlocks at the entryport and discharge port of the reaction vessel.
 18. A process forpyrolyzing discarded tires, comprising:introducing whole tires into areactor; preheating the whole tires to a level of 300° to 450°Fahrenheit; pyrolyzing the tires in a pyrolysis reaction vessel atbetween 1000° and 1100° Fahrenheit and oxygen limited hydrocarbon vaporatmosphere at between -5 and 20 PSIG to produce a substantiallypyrolyzed solid phase and a vapor phase; and separating said vapor phaseto produce oil and gas and dust.
 19. A process as in claim 18, whereinsaid pyrolizing step includes directly, internally heating the tires ina reaction vessel using microwave energy substantially in the absence ofartificially introduced oil heating media.
 20. A process as in claim 18,wherein the separation of the vapor phase comprises:condensing at leastone hydrocarbon fraction from said vapor phase; and separating saidfraction from the residual fuel gas.
 21. A process as in claim 20wherein said condensate and said hydrocarbon fraction are cooled by acombination of direct contact and indirect heat exchange.
 22. A processas in claim 18, wherein the hydrocarbon atmosphere in the reactionvessel is isolated from air by the use of an inert purge gas seal andairlocks at the entry and discharge ports of the sealed reaction vessel.23. A process as in claim 18, including separating said solid phase toremove metals and after said separation cooling said pyrolyzed solidphase after it exits the pyrolysis reactor.
 24. A process as in claim23, wherein pyrolyzed solid phase is cooled to less than 120° Fahrenheitby passing said solid phase in indirect heat exchange with water in anindirect heat exchanger.
 25. A process as in claim 24 wherein there isfurther included the steps including:physically separating trash fromthe solid phase by passing the solid phase through a relatively coarsescreen; discarding the trash; and recycling at least a portion of thepyrolyzed material to the indirect heat exchanger of said solid phase.26. A process for pyrolyzing discarded tires, comprising:A. feedingwhole tires to a preheater; B. preheating the whole tires in thepreheater using steam; and C. pyrolyzing the whole tires in a reactor bydirect, internal heating substantially in the absence of artificiallyintroduced oil heating media to produce vapor and solids.
 27. A processof claim 26, wherein there is included the steps ofD. processing thevapor from the reactor to separate vapor from dust; E. After Step D,separating the vapor into gas and oil.
 28. A process of claim 27,wherein there is included the steps of:F. processing the solids toseparate carbon black from trash and then cooling the carbon black; G.pellatizing the carbon black.
 29. A process of claim 28, wherein thereis included the steps of:H. separating carbon black dust from the trashof Step F; I. cycling the carbon black dust from Step H to thepellatizing Step G; J. cycling the carbon black dust of Step D to thepellatizing Step G.
 30. A process of claim 29, wherein step Gincludes:(1) cooling the dust; (2) milling the dust; (3) wetting thedust; (4) converting the wetted dust to pellets; (5) drying the pellets.31. A process of claim 26, wherein Step C includes introducing microwaveenergy into the reactor.
 32. A process for pyrolyzing discarded tires,comprising:A. feeding the tires to a pyrolysis reactor; B. pyrolyzingthe tires in the reactor by direct, internal heating substantially inthe absence of artificially introduced oil heating media to producevapor and solids, such internal, direct heating being by microwaveenergy.
 33. The process of claim 1,wherein prior to the pyrolyzing stepthere is included the steps of:pyrolyzing the tires in an indirectlythermal radiation heated pyrolysis reaction vessel at a temperature andpressure and for a reaction time sufficient to cause the tires todissociate into, in part, a solid phase having metals and hydrocarbonstherein; and removing the metals from the sold phase.
 34. The process ofclaim 18, wherein prior to the pyrolyzing step there is included thesteps of:pyrolyzing the tires in an indirectly thermal radiation heatedpyrolysis reaction vessel at between 800° and 1000° F. and oxygenlimited hydrocarbon vapor atmosphere at between -5 to 20 PSIG to producea vapor phase and a solid phase, the solid phase containing metals andhydrocarbons; generating the metals from the solid phase.
 35. Theprocess of claim 26, wherein prior to the pyrolyzing step, there isincluded the steps of:pyrolyzing the tires in an indirectly thermalradiation heated pyrolysis reaction vessel to produce a vapor phase anda solid phase, the solid phase containing metals and hydrocarbons;separating the metals from the solid phase.